PostgreSQL is a pretty good database, and I enjoy working with it. However, there is an implementation detail that not everyone knows about, which can drastically affect table performance. What is this mysterious feature? I am, of course, referring to foreign keys. Foreign keys are normally a part of good database design, and for good reason. They inform about entity relationships, and they verify, enforce, and maintain those relationships. Yet all of this comes at a cost that might surprise you.

With the release of PostgreSQL 8.4, the community gained the ability to use CTE syntax. As such, this is a fairly old feature, yet it’s still misunderstood in a lot of ways. At the same time, the query planner has been advancing incrementally since that time. Most recently, PostgreSQL has gained the ability to perform index-only scans, making it possible to fetch results straight from the index, without confirming rows with the table data.

I’ve managed to convince my employer to open source one of the tools I recently wrote. That tool goes by the name of walctl, and I believe the importance of this kind of tool can not be overstated. The PostgreSQL Write Ahead Log (WAL) files are key to crash recovery, point in time recovery, and all standby use not derived from streaming replication. WAL files are extremely critical to proper database operation.

There comes a time in every DBA’s life, that he needs to add functionality to his database software. To most DBAs, and indeed for most databases, this amounts to writing a few stored procedures or triggers. In extremely advanced cases, the database may provide an API for direct C-language calls. PostgreSQL however, has gone above and beyond this for several years, and have continuously made the process easier with each iteration.

Recently, I’ve come to the conclusion my tastebuds are changing somewhat drastically. How so? As it turns out, where once I couldn’t even tolerate medium heat, and Taco Bell Medium sauce packets were the equivalent of agony, now all commonly available hot sauces only impart a mild zip. Tabasco? Watery vinegar. Frank’s Red Hot? Tomato sauce. Cholula? Ketchup. Sriracha? Garlic ketchup. Insanity, to put it bluntly, and it was becoming a problem.